win32: different method to force window aspect ratio

The code used WM_WINDOWPOSCHANGING to force an spect ratio. This didn't
behave well if the left/top window borders were used for resizing.
Resizing with these borders changed the screen position of the right/bottom
as well, which is unintuitive and annoying.

Use WM_SIZING instead. Unlike WM_WINDOWPOSCHANGING, WM_SIZING knows about
which border is being used for resizing and can act accordingly.

Note that the calculated window size doesn't necessarily match with the
size mplayer calculates, but this problem exists on x11 as well.

1 files changed, 53 insertions, 15 deletions

diff --git a/libvo/w32_common.c b/libvo/w32_common.c
index 563fedeafa..9d9812db74 100644
--- a/libvo/w32_common.c
+++ b/libvo/w32_common.c
@@ -102,6 +102,38 @@ static const struct mp_keymap vk_map[] = {
     {0, 0}
 };
 
+static void vo_rect_add_window_borders(RECT *rc)
+{
+    AdjustWindowRect(rc, GetWindowLong(vo_window, GWL_STYLE), 0);
+}
+
+// basically a reverse AdjustWindowRect (win32 doesn't appear to have this)
+static void subtract_window_borders(RECT *rc)
+{
+    RECT b = { 0, 0, 0, 0 };
+    vo_rect_add_window_borders(&b);
+    rc->left -= b.left;
+    rc->top -= b.top;
+    rc->right -= b.right;
+    rc->bottom -= b.bottom;
+}
+
+// turn a WMSZ_* input value in v into the border that should be resized
+// returns: 0=left, 1=top, 2=right, 3=bottom, -1=undefined
+static int get_resize_border(int v) {
+    switch (v) {
+    case WMSZ_LEFT: return 3;
+    case WMSZ_TOP: return 2;
+    case WMSZ_RIGHT: return 3;
+    case WMSZ_BOTTOM: return 2;
+    case WMSZ_TOPLEFT: return 1;
+    case WMSZ_TOPRIGHT: return 1;
+    case WMSZ_BOTTOMLEFT: return 3;
+    case WMSZ_BOTTOMRIGHT: return 3;
+    default: return -1;
+    }
+}
+
 static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
     RECT r;
     POINT p;
@@ -130,21 +162,26 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM l
             mp_msg(MSGT_VO, MSGL_V, "[vo] resize window: %d:%d\n",
                    vo_dwidth, vo_dheight);
             break;
-        case WM_WINDOWPOSCHANGING:
+        case WM_SIZING:
             if (vo_keepaspect && !vo_fs && WinID < 0) {
-                WINDOWPOS *wpos = (WINDOWPOS*)lParam;
-                int xborder, yborder;
-                r.left = r.top = 0;
-                r.right = wpos->cx;
-                r.bottom = wpos->cy;
-                AdjustWindowRect(&r, GetWindowLong(vo_window, GWL_STYLE), 0);
-                xborder = (r.right - r.left) - wpos->cx;
-                yborder = (r.bottom - r.top) - wpos->cy;
-                wpos->cx -= xborder; wpos->cy -= yborder;
-                aspect_fit(global_vo, &wpos->cx, &wpos->cy, wpos->cx, wpos->cy);
-                wpos->cx += xborder; wpos->cy += yborder;
+                RECT *rc = (RECT*)lParam;
+                // get client area of the windows if it had the rect rc
+                // (subtracting the window borders)
+                r = *rc;
+                subtract_window_borders(&r);
+                int c_w = r.right - r.left, c_h = r.bottom - r.top;
+                float aspect = global_vo->aspdat.asp;
+                int d_w = c_h * aspect - c_w;
+                int d_h = c_w / aspect - c_h;
+                int d_corners[4] = { d_w, d_h, -d_w, -d_h };
+                int corners[4] = { rc->left, rc->top, rc->right, rc->bottom };
+                int corner = get_resize_border(wParam);
+                if (corner >= 0)
+                    corners[corner] -= d_corners[corner];
+                *rc = (RECT) { corners[0], corners[1], corners[2], corners[3] };
+                return TRUE;
             }
-            return 0;
+            break;
         case WM_CLOSE:
             mplayer_put_key(KEY_CLOSE_WIN);
             break;
@@ -421,16 +458,17 @@ static int reinit_window_state(void) {
         }
     }
 
+    SetWindowLong(vo_window, GWL_STYLE, style);
+
     r.left = window_x;
     r.right = r.left + vo_dwidth;
     r.top = window_y;
     r.bottom = r.top + vo_dheight;
-    AdjustWindowRect(&r, style, 0);
+    vo_rect_add_window_borders(&r);
 
     mp_msg(MSGT_VO, MSGL_V, "[vo] reset window bounds: %ld:%ld:%ld:%ld\n",
            r.left, r.top, r.right - r.left, r.bottom - r.top);
 
-    SetWindowLong(vo_window, GWL_STYLE, style);
     SetWindowPos(vo_window, layer, r.left, r.top, r.right - r.left,
                  r.bottom - r.top, SWP_FRAMECHANGED);
     // For some reason, moving SWP_SHOWWINDOW to a second call works better